In the case of a pneumatic tire used on a snowy road and a frozen road in winter (“winter tire”, hereinafter), emphasis is placed on driving performance on an especially slippery frozen road. More specifically, there is employed a method in which the land ratio of a tread surface is increased to increase the ground-contact area, or there is employed a method in which the tread central portion having a long ground-contact length in the tire circumferential direction is formed with a rib-like land on which a sipe is disposed. In any of these methods, however, the driving-in-snow performance, especially the driving performance in deep snow is prone to deterioration.
The present invention has been accomplished in view of the above-mentioned problem, and it is thus an object of the present invention to provide a winter tire capable of preventing a deterioration in the driving performance on frozen roads and, in fact, capable of enhancing the driving-in-snow performance, especially the driving performance in deep snow.